One of the earliest drugs used to treat patients with HIV infections was the nucleotide analog AZT. A nucleotide analog has a structure and function similar to a nucleotide. Some of the nucleotide analogs being used to treat HIV infections are called dideoxy-nucleotides. Dideoxy nucleotides include a ribose sugar that lacks both a 2' and 3' hydroxyl group. Based on what you know about nucleic acid synthesis, what effect do you think these analogs have on nucleic acid synthesis?